I am looking for additional information on my husband's G-Grandmother, Mamie (Usrey) Haggard.

This is what I have on her:
* Born Feb 1880 to Philip Charles Usrey and Sarah Ann Simmons, in Spring Valley, Cherokee, Kansas (1880 Census - mis-spelled as Marvie)
* 1885 Age 5, in Spring Valley, Cherokee, Kansas (Kansas State Census Collection, 1855-1925 - mis-spelled as Manie)
* Married John William Haggard 14 May 1899, in Joplin, Jasper, Missouri (Missouri Marriage Records, 1805-2002 - mis-spelled as Usery and Hoggard)
* 1900 Age 20, in Joplin, Jasper, Missouri (1900 Census)
* Children:
-Stephen S Haggard (1900-1960) [Listed as "Lewis" on 1900 Census??]
-Vernon T Haggard (1902-1960)
-Forrest W Haggard (1903-1976)
-Retha F Haggard (1906-?)

I have not been able to find anything on her between 1885 and 1899 or her death/burial. There is also a rumor in my husband's family that she was of Native American descent, I have not been able to confirm or deny. The Usrey line seems quite researched, yet there's not a lot on her. Any suggestions on where else I should look? I'm kinda new to genealogy and familiar with ALL of the resources available.

Thanks in advance for any help.